1. Field of the Invention
The present invention relates to N-[.omega.-(methyl),.omega.-(silyl)]alkyl-N-organocarboxamides, to oligomeric or polycondensed Si-containing compounds thereof, or mixtures of the corresponding monomeric, oligomeric and polycondensed Si-containing compounds, and their use as adhesion promoters and for the coating of surfaces.
The invention also relates, firstly, to a process for preparing N-[.omega.(methyl),.omega.-(silyl)]alkyl-N-organocarboxamnides by a hydrosilylation reaction in the presence of a rhodium-containing catalyst, and, secondly, to a process for preparing oligomeric or polycondensed Si-containing compounds or mixtures thereof starting from N-[.omega.-(methyl),.omega.-(silyl)]alkyl-N-organocarboxarnides.
2. Description of the Background
Description of the use of monomeric and polycondensed N-(arkoxysilyl)organocarboxamides with alkylene, alkarylene, aralkylene, cycloalkylene or arylene groups inserted between the nitrogen of the carboxamide group and the silicon of the silyl group has to date been limited to just a few studies. In these studies, the hydrocarbon groups, with the exception of alkarylene and aralkylene groups, are predominantly in the form of .omega.,.omega.-substituted species.
Examples of known applications for such organosilylcarboxamides are their use as catalysts for preparing dialkyl carbonates from alkanols (EP 0 428 802 Al), their use as adhesion promoters or for the coating of surfaces (DE-C 22 54 117), or as additives in RTV silicone compositions (U.S. Pat. No. 4,695,603). In contrast, mono- and di-(N-methylacetamido)silanes substituted directly on the nitrogen of the acetamido group by silyl find application, for example, for the endgroup modification of hydroxyl-terminated polydimethylsiloxanes (U.S. Pat. No. 5,373,079) or are employed as free-radical hardeners in moisture-crosslinking, pressure-sensitive, silicone based adhesive systems (U.S. Pat. No. 5,508,360).
Cyclic N-.omega.-(alkoxysilyl)organocarboxamides with an unbranched alkyl group between the nitrogen and silicon have been obtained by hydrosilylation of cyclic .omega.-alkenylcarboxamides and hydridosilanes in the presence of a Pt catalyst, for example by hydrosilylating N-allyl-2-pyrrolidone with a hydridosilane of the type HSiR'.sub.n (OR).sub.3-n where R and R' are hydrocarbon groups and n is 1, 2 or 3 (EP 0 392 509 BI).
The hydrosilylation of cyclic .omega.-alkenylcarboxamides can also be carried out with SiH-functional polysiloxanes (EP 0 450 900 Al). Siloxanes modified in this way are used to treat glass fibers, as foam stabilizers, or are employed as additives for cosmetics.
A further synthesis route for the provision of cyclic silyl-substituted carboxamide is opened up by the amidoalkylation of N-(chloromethyl)amides with N-(trimethylsilyl)amines or -amides (N.A. Anisimova et al., Zh. Obshch. Khim. 53 (5) (1983), 1198-1199).
A cyclic N-1-(alkoxysilyl)organocarboxamide with a branched alkyl group between the nitrogen of the carboxamide and the silicon of the silyl group, N-1-(triethoxysilyl)ethyl-2-pyrrolidone, has been obtained by hydrosilylating N-vinyl-2-pyrrolidone with triethoxysilane in the presence of a rhodium complex catalyst in tetrahydrofuran, with a yield of 72.6%, and has been tested for its pharmacological properties (T.G. Shchekina et al., Khim.-Farm Zh., 19 (2) (1985), 165-167; CA Vol. 103 (1985), 54137 p).
In addition, syntheses of monomeric and oligomeric methylsilyl-lactam structures starting from [chloro(methyl)]methyl/chlorosilanes (A. I. Albanov et al., Zh. Obshch. Khim. 52 (1) (1983), 246-248) or [chloro(methyl)]methyl/methoxysilanes (L. M. Khananashvili et al., Zh. Obshch. Khim. 52 (9) (1982), 2095-2097) are known. In general, the demand nowadays is for synthesis routes with a very low proportion of chlorine-containing starting materials.
In many products an extremely low chloride content is desired. Higher chloride contents may adversely affect the hydrolysis characteristics and the storage stability of organosilanes and organosiloxanes. Furthermore, in many possible fields of application, for example supports or components for electronic circuits, even small amounts of chloride are undesirable, so that, for example, products obtainable in accordance with DE-C 22 54 117 are nowadays of only limited commercial interest for such applications.
DE-C 22 54 117 discloses the hydrolysis of .beta.-chloroethylalkoxysilanes and the reaction of the resulting siloxane with an alkylamine or with other substitution products of ammonia.
Another disadvantage of many organopolysiloxanes is their relatively poor solubility, especially in water.